4.9 GHz异帧干扰问题研究

相对2.6 GHz频段,4.9 GHz频段可以通过灵活的帧结构配置满足上行大带宽的行业应用需求,但异帧结构组网可能导致基站和终端之间存在交叉时隙干扰,因此研究4.9 GHz的异帧干扰问题是非常必要的。基于3D-UMa传播模型,研究了4.9 GHz频段1D:3U:1S和5D:3U:2S帧结构配置下的交叉时隙干扰问题,并结合当下行业网需求现状给出了不同场景下的4.9 GHz帧结构按需配置建议,以及干扰管理解决方法,为5G行业网帧结构部署和站址规划提供了理论指导。     

基于FT245RL和FPGA的6路数据采集系统设计

针对大规模数据采集过程中存在数据量大与传输速度慢的矛盾,文章设计了基于FT245RL和FPGA的6路数据采集系统;该设计采用Xilinx公司的FPGA作为整个系统的核心,控制A/D转换器实现6路模拟数据的同步采集,并将转换后的数字信号存储到Flash中,最终通过USB2.0转换芯片将数据传输到上位机;试验表明,该数据采集系统能够满足对大容量数据实时采集、存储和上传的要求,具有工作稳定,可靠性高,传输速度快的特点,能够广泛应用于大规模数据的采集.     

Recessed ground microstrip line at 60 GHz and its application of band‐pass filter

The effect of finite‐size recessed ground on characteristic features of a microstrip transmission line is investigated and verified experimentally on alumina substrate of height 0.127 mm with ε_r = 9.8 at 60 GHz. A measured characteristic impedance of 238 Ω, effective dielectric constant of 3.09, and attenuation constant of 3.4 Np/m is achieved by using a recessed ground of dimensions (width × depth) 4.5 mm × 0.95 mm, below a 50‐Ω (on conventional ground plane) microstrip line. The effect of recessed ground on lumped equivalent circuit elements of microstrip line discontinuities including series‐gap, open‐end, and step discontinuities is also studied. To show the usefulness of recessed ground microstrip line, a prototype of fifth‐order Chebyshev‐type recessed ground end‐coupled band‐pass filter is designed and fabricated at 60 GHz. The filter exhibits measured insertion loss lower than 2.2 dB and return loss better than 13 dB over 3‐dB passband of 6% centered at 60 GHz. The measured results show good consistency with simulated results and confirm the usefulness of recessed ground plane microstrip line.     

基于分离式二极管的220GHz 高效率倍频器

在分离式二极管的基础上,实现了220 GHz高效率的二倍频器结构。该倍频器的电路在450 μm宽,2.7 mm长的50 μm石英基片上实现。测试结果表明,在室温下当驱动功率在46.4~164 mW时,在214~226 GHz的频段内能够实现大于16%的倍频效率。另外,当驱动功率在161 mW时,倍频器在218 GHz频点能够输出最高功率32 mW,并且在多个频点拥有高于20%的倍频效率。实验证明,所实现的二倍频器能够作为660 GHz倍频链路的驱动前级使用。     

D频段雷达传感器测距装置

针对其他各类传感器在极限条件下测距的局限性及微波雷达的全天候工作特点,提出了一种基于调频连续波(FMCW)工作方式的低功耗雷达测距装置。该装置功耗为500 mW,以120 GHz毫米波雷达传感器芯片为核心,使用STM32芯片进行控制及信号处理,基于ADF4169芯片完成所需的调频源输出。在对弱差频信号作滤波、放大、采集及频域处理后,通过上位机进行距离显示。实验结果表明:在1.5 m的单目标距离测试范围内,测距精度为3 cm。该系统的研究对推进D频段雷达传感器的实际应用具有重要价值。     

Millimeter‐wave antenna with wide‐scan angle radiation characteristics for MIMO applications

A three‐element quasi Yagi‐Uda antenna array with printed metamaterial surface generated from the array of uniplanar capacitively loaded loop (CLL) unit‐cells printed on the substrate operating in the band 25‐30 GHz is proposed. The metamaterial surface is configured to provide a high‐refractive index to tilt the electromagnetic (EM) beam from the two dipole antennas placed opposite to each other. The metamaterial region focuses the rays from the dipole antenna and hence increases the gain of the individual antennas by about 5 dBi. The antenna elements are printed on a 10 mil substrate with a center to center separation of about 0.5 λ ₀ at 28 GHz. The three‐element antenna covers 25‐30 GHz band with measured return loss of 10 dB and isolation greater than 15 dB between all the three ports. The measured gain of about 11 dBi is achieved for all the antenna elements. The three antenna elements radiate in three different directions and cover a radiation scan angle of 64°.     

粗糙表面毫米波传播信道特性研究及图论建模

针对具有不同表面粗糙程度的物体,对中心频点60 GHz、超宽带(Ultra Wideband,UWB)10 GHz电波传播信道的影响进行了研究.通过对在微波暗室环境下测量得到的单输入单输出(Single-Input Single-Output,SISO)信道冲击响应进行分析,提取并对比不同粗糙程度物体表面的信道散射与衰落特征参数,而后基于传播图仿真理论,改变模型参数对粗糙表面信道进行模型拟合,据此提出粗糙表面的可变阶次图论(Graph Theory,GT)模型.研究结果表明,不同粗糙程度表面的物体能够导致差异明显的信道衰减统计特征和时延域色散特性,采用不同散射系数的图论模型能够准确复现不同粗糙表面对传播信道的影响.研究成果对采用图论以较低复杂度,快速仿真复杂环境中的毫米波信道具有重要的意义.     

一种反演中高层大气密度的新方法

利用昆明电波观测站（25.6°N,103.8°E）的全天空流星雷达（All-sky Meteor Radar）和ST（Stratosphere-Troposphere）雷达于2014年特殊联合观测试验期间获取的数据,在确定了昆明地区中层顶位于流星峰值高度的情况下,根据温度梯度法得出的温度,使用大气物理压强温度公式,提出一种计算大气密度的新方法.研究发现,流星雷达的峰值高度与反演得到的大气密度走势基本相符,两台雷达得到的大气密度剖面存在很好的一致性.本文提出的方法,可以准确获得昆明地区上空85~94 km高度的大气密度,为探测中高层大气相关参数提供了一种新的途径.     

26 GHz室内簇的时变特性及建模研究

基于室内大规模单输入单输出（Single-Input Multiple-Output,SIMO）测试,开展了26 GHz毫米波无线信道簇变化量的时变特性建模研究.首先针对构建2020年信息社会的无线通信关键技术（Mobile and Wireless Communications Enablers for the Twenty-twenty Information Society,METIS）标准中分簇算法的不足进行改进,然后通过对功率时延谱求包络,来去除簇内射线及噪声对分簇结果的影响,在此基础上进行分簇会得到更加合理的结果.办公室环境下大规模虚拟天线阵列测试数据的分析结果表明,簇数目的变化量服从正态分布,经过不同时间簇数目变化量的均值和方差与二次函数较吻合.因此,将办公室场景下簇数目的变化量建模成均值和方差为二次函数的正态分布是合适的.     

UWB pulse design using constraint convex sets method

In this paper, we propose a constrained convex sets–based method for designing ultra‐wideband (UWB) pulse. The UWB pulses designed using earlier proposed methods either do not fit well in UWB spectral mask or require extra processing circuitry for pulses to fit in the UWB spectral mask. The proposed constraint sets–based method is flexible and optimum for the UWB mask. The pulse designed by the proposed method is Federal Communication Commission compliant and has an autocorrelation function similar to the Gaussian pulse. The bit error rate performance of time hopping binary phase shift keying using the proposed method and some of the existing methods such as Norman and Lee pulses and sixth derivative Gaussian pulse is analyzed in additive white Gaussian noise and Saleh‐Valenzuela channels. Pulse designed using the proposed method outperforms existing pulse design, and the same is verified through simulations. The proposed algorithm is flexible and can also be used to mitigate narrow band interference, multiband UWB pulse generation and any other Federal Communication Commission (or other regulatory body) compliant spectrum mask by modifying the parameter of the proposed constraint set(s).